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@ARTICLE{Krmer:889042,
author = {Krämer, Martina and Rolf, Christian and Spelten, Nicole
and Afchine, Armin and Fahey, David and Jensen, Eric and
Khaykin, Sergey and Kuhn, Thomas and Lawson, Paul and Lykov,
Alexey and Pan, Laura L. and Riese, Martin and Rollins,
Andrew and Stroh, Fred and Thornberry, Troy and Wolf,
Veronika and Woods, Sarah and Spichtinger, Peter and Quaas,
Johannes and Sourdeval, Odran},
title = {{A} microphysics guide to cirrus – {P}art 2:
{C}limatologies of clouds and humidity from observations},
journal = {Atmospheric chemistry and physics},
volume = {20},
number = {21},
issn = {1680-7324},
address = {Katlenburg-Lindau},
publisher = {EGU},
reportid = {FZJ-2020-05412},
pages = {12569 - 12608},
year = {2020},
abstract = {This study presents airborne in situ and satellite remote
sensing climatologies of cirrus clouds and humidity. The
climatologies serve as a guide to the properties of cirrus
clouds, with the new in situ database providing detailed
insights into boreal midlatitudes and the tropics, while the
satellite-borne data set offers a global overview.To this
end, an extensive, quality-checked data archive, the Cirrus
Guide II in situ database, is created from airborne in situ
measurements during 150 flights in 24 campaigns. The archive
contains meteorological parameters, ice water content (IWC),
ice crystal number concentration (Nice), ice crystal mean
mass radius (Rice), relative humidity with respect to ice
(RHice), and water vapor mixing ratio (H2O) for each of the
flights. Depending on the parameter, the database has been
extended by about a factor of 5–10 compared to earlier
studies.As one result of our investigation, we show that the
medians of Nice, Rice, and RHice have distinct patterns in
the IWC–T parameter space. Lookup tables of these
variables as functions of IWC and T can be used to improve
global model cirrus representation and remote sensing
retrieval methods. Another outcome of our investigation is
that across all latitudes, the thicker liquid-origin cirrus
predominate at lower altitudes, while at higher altitudes
the thinner in situ-origin cirrus prevail. Further,
examination of the radiative characteristics of in
situ-origin and liquid-origin cirrus shows that the in
situ-origin cirrus only slightly warm the atmosphere, while
liquid-origin cirrus have a strong cooling effect.An
important step in completing the Cirrus Guide II is the
provision of the global cirrus Nice climatology, derived by
means of the retrieval algorithm DARDAR-Nice from 10 years
of cirrus remote sensing observations from satellite. The in
situ measurement database has been used to evaluate and
improve the satellite observations. We found that the global
median Nice from satellite observations is almost 2 times
higher than the in situ median and increases slightly with
decreasing temperature. Nice medians of the most frequently
occurring cirrus sorted by geographical regions are highest
in the tropics, followed by austral and boreal midlatitudes,
Antarctica, and the Arctic. Since the satellite
climatologies enclose the entire spatial and temporal Nice
occurrence, we could deduce that half of the cirrus are
located in the lowest, warmest (224–242 K) cirrus layer
and contain a significant amount of liquid-origin cirrus.A
specific highlight of the study is the in situ observations
of cirrus and humidity in the Asian monsoon anticyclone and
the comparison to the surrounding tropics. In the
convectively very active Asian monsoon, peak values of Nice
and IWC of 30 cm−3 and 1000 ppmv are detected around
the cold point tropopause (CPT). Above the CPT, ice
particles that are convectively injected can locally add a
significant amount of water available for exchange with the
stratosphere. We found IWCs of up to 8 ppmv in the Asian
monsoon in comparison to only 2 ppmv in the surrounding
tropics. Also, the highest RHice values
$(120 \%–150 \%)$ inside of clouds and in clear sky
are observed around and above the CPT. We attribute this to
the high H2O mixing ratios (typically 3–5 ppmv) observed
in the Asian monsoon compared to 1.5 to 3 ppmv found in
the tropics. Above the CPT, supersaturations of
$10 \%–20 \%$ are observed in regions of weak
convective activity and up to about $50 \%$ in the Asian
monsoon. This implies that the water available for transport
into the stratosphere might be higher than the expected
saturation value.},
cin = {IEK-7},
ddc = {550},
cid = {I:(DE-Juel1)IEK-7-20101013},
pnm = {244 - Composition and dynamics of the upper troposphere and
middle atmosphere (POF3-244)},
pid = {G:(DE-HGF)POF3-244},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000583697500003},
doi = {10.5194/acp-20-12569-2020},
url = {https://juser.fz-juelich.de/record/889042},
}